Modification of ash fusion behavior of coal with high ash fusion temperature by red mud addition

Xiao, Huixia; Liu, Quanrun; Ji, Shaohua; Fan, Hongli; Xu, Mei‐Ling; Guo, Qianqian; Ma, Mingjie; Ma, Xiuwei

doi:10.1016/j.fuel.2016.12.012

Cited by 45 publications

(23 citation statements)

References 39 publications

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“…As shown in Figure 2a, for the A S , with the increase of A X , the AFTs of the mixture A S-X was greater than 1500 C (0-11.31%) and then decreased rapidly (11.31-25.67%); when the amount of A X was 24.41%, the FT of the mixture A SX reached 1380 C. As shown in Figure 2b, for A Z , with the ratio of A X increased, AFT of the mixture A Z-X showed no change [the change in trends cannot be detected, limited by the instrument (0-10.20%), rapid reduction (Figure 2b)]. Mg 2+ and Fe 2+ intended to combine with O 2− and formed the structure ─O─M─O─ (M═Ca, Mg, Fe) because the ionic radius of Mg 2+ and Fe 2+ were smaller than that of Ca 2+ , 14,27 and they were easier to destroy with the network structure of mullite and quartz, which reduced AFTs significantly. Compared with Figures 1 and 2, despite the high CaO content (A H :50.07%; A X :37.75%), the addition amount of A H was much higher than that of A X when AFTs of the mixture met the condition of the EFG.…”

Section: Aft Variation Of the Mixture A Hac-xmentioning

confidence: 99%

“…This showed that Ca 2+ , Mg 2+ , and Fe 2+ might have a certain synergistic effect in reducing AFTs. Mg 2+ and Fe 2+ intended to combine with O 2− and formed the structure ─O─M─O─ (M═Ca, Mg, Fe) because the ionic radius of Mg 2+ and Fe 2+ were smaller than that of Ca 2+ , 14,27 and they were easier to destroy with the network structure of mullite and quartz, which reduced AFTs significantly. Simultaneously this was consistent with their B/A ratio.…”

Section: Aft Variation Of the Mixture A Hac-xmentioning

confidence: 99%

“…9 According to ash chemical composition, coal can be divided into high silica alumina coal (HSAC, the content of Al 2 O 3 and SiO 2 are >80%), high silicon aluminum ratio coal (SiO 2 /Al 2 O 3 > 2), high calcium coal (HCC, CaO >15%) and high iron coal (Fe 2 O 3 > 15%). 13,14 Whichever content of SiO 2 , A1 2 O 3 , Fe 2 O 3 , and CaO is higher will increase AFTs. 13,14 Whichever content of SiO 2 , A1 2 O 3 , Fe 2 O 3 , and CaO is higher will increase AFTs.…”

mentioning

confidence: 99%

“…12 Usually, acidic oxide can increase AFT, and alkaline oxide can reduce AFT. 13,14 Whichever content of SiO 2 , A1 2 O 3 , Fe 2 O 3 , and CaO is higher will increase AFTs. Therefore, the high-AFT coal is divided into HSAC, high alumina coal (HAC, Al 2 O 3 > 38%), HCC (CaO > 35%), and other high alkali coal.…”

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confidence: 99%

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Regulation of ash fusion behaviors for high aluminum coal by high calcium coal addition

Xiao

2020

Asia-Pacific J Chem Eng

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To meet the requirement of liquid slag tapping entrained-flow gasification, two kinds of high ash fusion temperatures (AFTs) coals with significant difference in ash chemical composition (high aluminum coal: Al 2 O 3 > 38%, Sunjiahao coal, and Shajuzi coal; high calcium coal: CaO > 35%, Hebi coal, and Xinjiang coal) were selected. The ash fusion behaviors of blending coal were investigated. The results showed that blending coal could significantly reduce the AFTs of high-AFT coal. The formation of high melting point minerals led to the increase of AFTs (high aluminum coal: mullite, corundum, and cristobalite; high calcium coal: lime and periclase). Xinjiang coal reduced AFTs more obviously than that of Hebi coal because of the differences in the total amount of alkali oxides, Fe 2 O 3 and MgO. The effect of CaO on AFTs was determined by the amount of CaO. CaO, Fe 2 O 3 , and MgO promoted the formation of low-melting eutectic [anorthite, gehlenite, spinel, pyrope, and ringwoodite (Fe-rich)] and made AFTs low when the mass ratios of high calcium coal were low. On the contrary, the high content of CaO increased AFTs.FactSage7.0 software is a very effective way to explore the effect of mineral transformation on AFTs. K E Y W O R D Scoal blending, coal preparation principle, high ash fusion temperature, modification mechanism

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Section: Aft Variation Of the Mixture A Hac-xmentioning

confidence: 99%

Section: Aft Variation Of the Mixture A Hac-xmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Regulation of ash fusion behaviors for high aluminum coal by high calcium coal addition

Xiao

2020

Asia-Pacific J Chem Eng

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“…6334 (Theis et al 2006). Thus, S may be captured by Ca compounds, the formation of stable sulfates CaSO4 is the dominant reaction path (Aho and Ferrer 2005;Li and Fang 2015;Mueller et al 2006;Xiao et al 2017). At the high temperature condition, the oxidation environment and the presence of Fe, Si, and Al remarkably promoted the sulfur fixation reaction of Ca.…”

Section: Effect Of Excess Air Coefficientmentioning

confidence: 99%

Fouling and Slagging Characteristics during Co-combustion of Coal and Biomass

Zhu¹,

Yang²,

Chen³

et al. 2017

BioResources

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The effects of different kinds (cotton stalk, rice husk, and sawdust) and proportions (0%, 10%, 20%, and 30% based on weight) of biomass and operating conditions (temperature and excess air coefficient) were evaluated relative to the ash deposition characteristics during the cofiring of Huang Ling (HL) coal with biomass. The experiments were performed in a drop-tube furnace. The chemical compositions and mineral phase characteristics of the collected ash particles were analyzed using scanning electron microscopy with energy dispersive Xray (SEM-EDX) and X-ray diffraction (XRD), respectively. The results showed that the most severe agglomeration, from co-firing coal with cotton stalk, was due to the higher content of alkali metals, especially K. The amount of K in the ash increased with an increasing proportion of cotton stalk, and ultimately, agglomeration was more serious. When the combustion temperature increased from 1050 °C to 1300 °C, the dystectic solid compounds were transformed into eutectic compounds. The increased excess air coefficient accelerated the sulfur reaction, but did not relieve the heavy sintering. Consequently, limiting the content of biomass in the fuel blends, maintaining a lower combustion temperature, and a suitable level of excess air were determined to be necessary for the co-firing of coal and biomass.

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Synergistic effect of CaO and MgO addition on coal ash fusibility in a reducing atmosphere

Xin

Liu

et al. 2019

Asia-Pacific J Chem Eng

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During coal gasification in entrained-flow slagging gasifiers, the addition of additives is a promising method to improve coal ash fusibility. In some cases, mixed additives are more effective in decreasing ash fusibility than single additive addition with the same content added. However, mechanisms of mixed additive addition for improving ash melting are scarce. In this study, the effect of CaO, MgO, and their mixtures on the ash flow temperature (FT) of Chinese bituminous coal was investigated. The results show that the single addition of CaO or MgO influenced the ash FT of the test coal sample. The addition of CaO and MgO mixture synergistically decreased the ash FT relative to their single addition. When the ratio of CaO to MgO was 5:5 (mass ratio) in the mixture, the FT decreased to 1297°C, which is 69°C and 110°C lower than that of the single addition of CaO and MgO, respectively. The formation of a lowtemperature eutectic from the interactions between anorthite and olivine caused such synergistic effects. KEYWORDS ash flow temperature, CaO and MgO mixture, low-temperature eutectic, synergistic effect

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Modification of ash fusion behavior of coal with high ash fusion temperature by red mud addition

Cited by 45 publications

References 39 publications

Regulation of ash fusion behaviors for high aluminum coal by high calcium coal addition

Regulation of ash fusion behaviors for high aluminum coal by high calcium coal addition

Fouling and Slagging Characteristics during Co-combustion of Coal and Biomass

Synergistic effect of CaO and MgO addition on coal ash fusibility in a reducing atmosphere

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